"Six By Sondheim" is a new HBO documentary that takes a look at the life and art of musical theatre legend Stephen Sondheim through six of his iconic songs. Directed by Tony winner James Lapine, the film contains archival footage as well as new musical segments directed by Todd Haynes, Autumn de Wilde and Lapine. In this special peek at the film (courtesy of HBO), Sondheim discusses the challenges of writing new material, while Darren Criss, Jeremy Jordan, America Ferrera Laura Osnes, Montego Glover, Nathan Lane and the film's executive producer Frank Rich discuss why Sondheim is an icon of the musical theatre. "Six By Sondheim" debuts Dec. 9 on HBO.